1. Field of the Invention
The present invention relates to a light emitting module and an automotive headlamp used in an automobile, etc.
2. Description of the Related Art
Recently, for the purpose of long life or reduction in power consumption, a technique has been developed in which a light emitting module having a light emitting element, such as an LED (Light Emitting Diode), is used as a light source for emitting strong light, such as a lamp unit that emits light toward the front of a vehicle. However, in order to be used in such an application, a light emitting module is required to emit light with high luminance. Herein, in order to improve, for example, the extraction efficiency of white light, a lighting device has been proposed, the lighting device comprising: a light emitting element that mainly emits blue light; a yellow phosphor that mainly emits yellow light by being excited with the blue light; and a blue-transmitting/yellow-reflecting means through which the blue light from the light emitting element is transmitted and by which the light from the yellow phosphor, the wavelength of which is larger than or equal to that of the yellow light, is reflected (for example, Japanese Patent Application Publication No. 2007-59864).
However, when converting a wavelength of light by using a common powdered phosphor, the luminance of the light is weakened when the light hits the particle of the phosphor, and hence it is difficult to realize high use efficiency of light. Therefore, a structure has been proposed in which a ceramic layer that is arranged in the path of the light emitted by, for example, a light emitting layer, is provided (for example, Japanese Patent Application Publication No. 2006-5367).
In recent years, semiconductor light emitting diodes (LEDs), which are small in size and light in weight and excellent in luminous efficiency, are increasingly used in automotive lamps including headlamps. The light emitting surface of an LED tip used as a light source is usually rectangular-shaped. Accordingly, in the automotive headlamp using an LED as a light source, a shade for forming a cutoff line is separately needed when a light distribution pattern for low beam is to be formed.
However, because part of the light, which has been emitted from a light source, becomes useless due to such a shade, further improvement is required from the viewpoint of the utilization rate of light.